Lighting Up Electrochemiluminescence-Inactive Dyes via Grafting Enabled by Intramolecular Resonance Energy Transfer.

Due to near-zero optical background and photobleaching, electrochemiluminescence (ECL), an optical phenomenon excited by electrochemical reactions, has drawn extensive attention, especially for ultrasensitive bioassays. Developing diverse ECL emitters is crucial to unlocking their multiformity and performances but remains a formidable challenge due to the rigorous requirements for ECL. Herein, we report a general strategy to light up ECL-inactive dyes in an aqueous solution via grafting, a well-developed concept for plant propagation since 500 BCE. As a proof of concept, a series of luminol donor-dye acceptor-based ECL emitters were grafted with near-unity resonance energy transfer (RET) efficiency and coarse/fine-tunable emission wavelengths. Rather than the sophisticated design of new skeleton-based molecules to meet all of the prerequisites for ECL in a constrained manner, each unit in the proposed ECL ensemble performed its functions maximally. As a result, beyond traditional two-dimensional (2D) ones, a three-dimensional (3D) coordinate biosensing system, simultaneously showing a calibration curve and selectivity, was established using the new ECL emitter. This lighting up strategy would generally address the scarcity of ECL emitters and enable unprecedented functions.